Deduplicate customer records by fuzzy key

Python data engineering interview problem. Difficulty: intermediate. Pattern: Deduplication. About 15 minutes. Part of the Pro drill bank.

A CRM export repeats the same customer under slightly different keys. Dedup must collapse those rows using the fuzzy key the prompt defines, not a naive exact match only.

Deduplicate customer records by the fuzzy key described in the prompt.

Requirements

• Two rows with the same fuzzy key keep one surviving record.
• Preserve a deterministic survivor (usually first-seen).

Constraints

• rows: customer records (dicts or tuples).
• Exact duplicates and fuzzy duplicates both appear.

Examples

Input: dedupe_customers([{'name': ' Ann ', 'zip': '94110', 'updated_at': '2026-01-01', 'id': 1}, {'name': 'ann', 'zip': '94110', 'updated_at': '2026-02-01', 'id': 2}]) Output: [{'name': 'ann', 'zip': '94110', 'updated_at': '2026-02-01', 'id': 2}] This input follows the stated rules and produces this output.

Topics: lakebench, python, deduplication.

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